Experts say 3.7 million are blighted by the illness – an increase of 1.9 million since 1998 – and they fear it is only the tip of the iceberg.

A further 12.3 million are at increased risk of lifestyle-driven Type 2, a preventable but deadly condition caused by the UK’s obsession with sugary snacks.

The epidemic last night prompted Diabetes UK to call for stricter restrictions on junk food advertising and a clampdown on supermarket price promotions.

Chief executive Chris Askew said: “Diabetes is the fastest growing health crisis of our time; and the fact diagnoses have doubled in just 20 years should give all of us serious pause for thought.

“Both Type 1 and Type 2 are serious conditions that can lead to devastating complications such as amputation, blindness, kidney disease, stroke and heart disease if people don’t receive a timely diagnosis and begin receiving the right care.

“We want the Government to recognise the seriousness of the growing crisis, take action to help those at increased risk, and help us turn the tables on this devastating condition.”

Type 1 sees the body automatically destroy its own insulin-producing cells but Type 2 is largely brought on by chronically unhealthy lifestyles.

The number of people diagnosed with both types has increased by almost 100,000 in just a single year, rising from 3,590,501 to 3,689,509.

The charity estimates there are one million people who have diabetes but are not aware of it.

It means 25 per cent of the UK population has, or could develop, the debilitating illness.

Diabetes now costs more than £10billion a year to treat – 10 per cent of the NHS budget.

Bradford has the UK’s highest prevalence of diabetes with one in 10 living with the condition. The national average is 6.6 per cent.

Tam Fry, of the National Obesity Forum, said: “For at least the last decade successive governments have been repeatedly warned the disease, triggered by obesity, could bring down the NHS. For the last 20 years no serious strategy has been produced to tackle it.”